It is generally known to protect electric or electronic devices or circuits from line-conducted electromagnetic irradiation. For this purpose, interference-suppression capacitors are provided, for example, which are connected via a mass frame ground connection to the circuit arrangement and via a compression spring to a metal housing. A disadvantage of this known configuration is that, as mechanical parts, the mass springs require space. Moreover, aging of the parts can cause the spring contact to the housing to deteriorate. Also, because of the long path between the interference-suppression capacitor and the ground connection part, emission of interference signals can still occur.
It is further known to use an electrically conductive adhesive agent between the circuit arrangement and the housing to provide capacitive coupling. German Unexamined Patent Application No. 38 37 206 describes using an adhesive agent to couple a discrete interference-suppression capacitor, situated on a circuit board, to a grounded metallic housing through a dielectric layer, thereby creating a capacitive coupling to the housing that is in series with the discrete capacitor on the circuit board. Although this arrangement offers a sufficiently high-frequency coupling of a circuit to ground, it cannot be used for hybrid circuits and, in any case, requires an electrically conductive housing. Moreover, the additional arrangement of a chip capacitor is needed.